You Get the Flu Way Less Than You Think

Instead of twice each winter, you might actually get the flu twice every 20 years

If it seems like you’re constantly getting the flu, you might be blaming the wrong bugs. A new study published in PLOS Biology suggests that after age 30, people generally only get the flu about twice a decade.

Researchers from Imperial College London looked at a single blood sample from 151 people in southern China and examined their flu antibody levels to the current strain of flu, as well as several historical strains prevalent over the last 40 years. They then estimated how many times people were infected and what happened to their antibodies at different points in their lives.

Young people got the flu more often, about once every other year. That might be because young people socialize more, the authors write. But once they hit age 30, rates flattened out; adults got the flu about twice every 20 years.

“A lot of people say once or twice a year they’ve got the flu, and that’s very unlikely to be true,” says Dr. Steven Riley, senior author of the study and reader at the Medical Research Council Centre for Outbreak Analysis and Modelling at Imperial College London. Sometimes flu can be mild—you may not even know you have it, but your sky-high antibody levels indicate otherwise, Riley says.

Though Riley is cautious to overinterpret the findings, the data was able to estimate infection rates across many years, which may one day prove valuable in vaccine applications, he says. “You could certainly think that down the road, this type of analysis would lead to a more sophisticated vaccine protocol—possibly the frequency with which you vaccinate and the doses with which you vaccinate could be optimized,” he says. “We can’t say what those optimal regimes would be based on this paper, but these nicely reproducible patterns suggest that that’s a good avenue to look for in the future.”

The Weird Benefit of Eating Salty Food

Too much salt can lead to heart disease, but there may be a healthy side to salt that hasn’t been appreciated — until now

If you’re an average American, chances are that you’re eating too much salt. But the latest research — which, the scientists stress, is still in its early stages — hints that there may be some benefits to salt that have gone unnoticed. Salt, it seems, may be an ancient way for the body to protect itself against bacteria.

Reporting in the journalCell Metabolism, Jonathan Jantsch, from the University of Regensburg in Germany, says that salt may be an effective way to ward off microbes. In a series of studies using both mice and human cells, he and his colleagues found that levels of sodium go up around an infection site, and that without salt, bacteria tend to flourish and grow better.

The discovery came about by accident, after Jens Titze, the study’s senior author, noticed that mice who had been bitten by their cage mates showed higher levels of sodium in their skin than those who were wound-free. Jantsch decided to find out whether the salt had something to do with the infection-fighting functions of the immune system.

He and his team conducted a series of experiments in which they subjected mouse and human cells to high levels of sodium chloride, and watched the immune cells activate. They also fed mice diets that were low and high in sodium, and then infected them with Leishmania major. The mice fed the higher amounts of sodium showed stronger immune responses to the wounds, and cleared their infections faster than the mice eating less salt. In fact, Jantsch speculates that certain skin cells may transport sodium preferentially to sites where bacterial populations are high in order to create another barrier preventing the microbes from entering deeper into the body.

That opens the possibility that salt may be an unrecognized contributor to the immune system, and possibly a remnant from the days before antibiotics, when mammals, including humans, needed some allies in the fight against microbes. After all, salt has been used for centuries to preserve food from spoiling in bacteria’s presence, so it makes sense that evolutionarily, sodium might have also been co-opted by the body in a similar way. “I really think salt is an unappreciated factor of immunity,” says Jantsch.

If that’s the case, then it may be possible to take advantage of salt-based dressings, for instance, to improve wound healing. Burn patients may benefit the most, since their skin, the first line of defense against microbes, is compromised. And for those with hyperactive immune responses, dialing down the concentration of sodium at specific areas might also be helpful. “We are interested in how this works, because it can have broad applications,” says Jantsch. “We can possibly target and boost sodium in situations where we need more salt if it’s deficient, and lower it in situations where there is salt overload and hypertension.” Already, some companies have produced wound dressings with enhanced sodium concentration as a way to help infections heal faster.

He stresses, however, that the results don’t mean high salt diets are now healthy — or advisable. His studies, even in mice, haven’t worked out exactly how salt in the diet affects the body’s ability to recruit the nutrient to fight infections. And to get the bacteria-fighting effect, the mice were fed a diet that was extremely high in sodium — 4%, compared to the average mouse chow which is only 0.2% to 0.3% sodium. “There is overwhelming data that tells you a high salt diet is detrimental to the heart,” he says. “We used one animal approach to look at the beneficial role of salt. So I would be hesitant to draw any conclusions for humans at this stage.” He and others are already setting up more experiments, however, to study how salt might become the next weapon in fighting infections.

5 Non-Diet Factors That Can Affect Your Weight

Weight control is influenced by more than your daily calorie intake

For years I’ve heard experts say, “Weight loss simply comes down to calories in versus calories out.” But throughout my years as a practitioner, that simple philosophy hasn’t rung true. I’ve seen clients break a weight loss plateau after increasing their calorie intake—swapping processed “diet” food for whole, nutrient-rich clean foods and changing up their meal balance and timing.

I’ve also found that stressed-out, sleep-deprived clients have a more difficult time losing weight, which has been backed by numerous studies. And now, research shows that a number of other lifestyle and environmental factors also play roles in influencing metabolism and weight control.

Here are five on my radar, and tips for combating them.

Artificial additives

Just-released animal research from Georgia State University found evidence that artificial preservatives used in many processed foods may be associated with metabolic problems, such as glucose intolerance and obesity. In rodents genetically prone to inflammatory gut diseases, the chemicals led to an increase in the severity and frequency of metabolic problems. Scientists believe the effects are due to changes in gut bacteria. When chemicals break down the mucus that lines and protects the gut, unhealthy bacteria come into contact with gut cells, which triggers inflammation, and as a result, changes in metabolism.

Combat it: This is preliminary research, but even more of a reason to read food labels and eat clean. When buying anything that comes in a box, bag, or jar, read the ingredient list first. My philosophy is that it should read like a recipe you could whip up in your own kitchen. For more info check out my previous post What Is Clean Eating?

Researchers from the University of Colorado at Boulder found that people who work the night shift burn fewer calories during a 24-hour period than those who work a normal schedule. The difference can lead to weight gain, even without an increase in calories. In other words, when you throw off your body’s circadian rhythm, your normal diet can suddenly become excessive due to a metabolic slowdown. This parallels research which found a relationship between body clock regulation, gut bacteria, and metabolism. When mice received gut bacteria from jet-lagged humans, they gained significant amounts of weight and had abnormally high blood sugar levels.

Combat it: If you work when most people are sleeping, or you travel through different time zones, seek out nutrient-rich foods that help boost satiety, increase metabolic rate, and regulate hunger, including fresh veggies and fruit, beans and lentils, nuts, ginger, hot peppers, and good old H2O. For more tips check out my previous post 9 Natural Appetite Suppressants That Actually Work.

University College London researchers found that over a four-year period, people who experienced weight discrimination or “fat shaming” gained weight, while those who did not shed pounds. Another study from Renison University College at the University of Waterloo found that over five months, women with loved ones who were critical of their weight put on even more pounds.

Combat it: You may not be able to control the type or amount of support you receive from others, but there are effective techniques for improving your personal mindset. For example, practicing mindfulness meditation has been shown to help reduce stress, lower hunger hormones, and prevent weight gain. In a study published in the Journal of Obesity, this practice led to a greater loss of belly fat, without following a calorie-counting diet. I teach it in my private practice and I devoted an entire chapter to meditation in my upcoming book, Slim Down Now($20, amazon.com). If you’re a newbie, check out UCLA’s online classes.

It may seem odd for a nutrition professor to study flame retardants. But one such professional at the University of New Hampshire found that these substances—which are found in everything from furniture to carpet padding and electronics—trigger metabolic and liver problems that can lead to insulin resistance, a major cause of obesity. Compared to a control group, rats exposed to these chemicals experienced dramatic physiological changes. In just one month, levels of a key enzyme responsible for sugar and fat metabolism dropped by nearly 50% in the livers of rats exposed to flame retardants. According to the researcher, the average person has about 300 chemicals in his or her body that are man made, and we’re only beginning to understand the possible effects.

Combat it: You can’t eliminate your exposure to synthetic substances, but you can limit it. You can now find natural products in nearly every shopping category, including cosmetics, cleaning supplies, toys, and household goods. For help, check out resources and guides from organizations like the Environmental Working Group.

It’s no surprise that we take after our parents when it comes to body type, but new research shows that the type of bacteria that live in our digestive systems are also influenced by genetics. That’s an important finding, because more and more research indicates that gut bacteria are strongly connected to weight control. Scientists at King’s College London found that identical twins had a similar abundance of specific types of gut bacteria, compared to non-identical twins. This indicates that genes strongly influence bacteria, since identical twins share 100% of their genes, while non-identical twins share about 50% of their genes. They also found that the presence of a specific type of bacteria was most influenced by genetics, and that type strongly correlated with leanness. In fact, transplanting this bacteria to the digestive systems of mice caused the animals to gain less weight than those that did not receive the bacteria.

Combat it: You can’t change your genetics, but there’s a great deal of research now about how you can transform your good gut bacteria. The top strategy: avoid artificial and processed foods, and load up on a variety of whole, plant-based foods, including vegetables and fruits, whole grains, beans and lentils, and fermented foods like kimchi and sauerkraut. For more about how to eat more plant-based foods, check out my previous post 5 Delicious Pasta Alternatives.

Cynthia Sass, MPH, RD, is Health’s contributing nutrition editor, and privately counsels clients in New York, Los Angeles, and long distance. Cynthia is currently the sports nutrition consultant to the New York Rangers NHL team and the Tampa Bay Rays MLB team, and is board certified as a specialist in sports dietetics.

4 Superfoods You Might Be Overeating

You can have too much of a good thing, even when it may be the healthiest food of all

When it comes to diet, you can totally have too much of a good thing. Even the healthiest foods, in big quantities, may have side effects. And today, with our increased zeal for superfoods, the risk of overdosing on certain power eats has multiplied. Here are my top culprits—plus how to stay balanced.

Kale

For nutrients and antioxidants per calorie, few foods compare to kale. But our current obsession with this leafy green may be overkill: Kale’s appearance on U.S. restaurant menus jumped nearly 400 percent from 2009 to 2013. And the number of new kale products introduced globally more than tripled between 2007 and 2012, per Innova Market Insights.

Women I know are whipping up a green juice (many of which contain far more kale than they could eat in one sitting concentrated into 16 ounces) in the morning, having kale salad for lunch and snacking on kale chips at night. The potential side effect? Kidney stones. Kale contains oxalate, which can bind with calcium to form stones. While other foods (like spinach) are higher in oxalate, megadoses of kale could make it a problem for those susceptible to stones.

The best balance:Choose a kale-rich green juice or a big kale salad per day. On days you have whole kale, you can still do green juice; just make one with a low-oxalate ingredient like cucumber and a variety of other vegetables.

One of the simplest (and yummiest) ways to get the recommended twice-weekly servings of ocean fare is to hit the local sushi joint. But plenty of busy women overrely on it.

While sushi does offer lean protein and heart- and brain-protective omega-3s, mercury in fish (from pollution) is a real concern. And it can be easy to OD on it via sushi, per a recent study. Researchers at Rutgers University interviewed 1,289 men and women about their sushi intake and tested fish samples. Among the tuna, eel, salmon and crab, tuna had the highest levels of mercury. Researchers estimated that mercury exposure for people who ate seven sushi meals consisting mostly of tuna per month exceeded the EPA’s recommendations. The scary part: Symptoms of mercury overexposure (vision issues, tingling fingers and muscle weakness) may not show up for months, or even at all.

The best balance: A good sushi option is a brown rice California roll; it’s made with crabmeat, so it’s fine twice a week. It’s best to limit bigger fish like certain types of mackerel and tuna, which tend to have more mercury—particularly if you’re pregnant, planning to get pregnant or nursing.

If you shop for cereals, energy bars, orange juice and bottled water, you’ve probably seen labels bragging about added nutrients. Check those labels carefully, however. Some cereals boast 100 percent of the daily value (DV) for many vitamins and minerals. While fortification helps ensure that you’re not lacking in nutrients like vitamin D, ingesting a total day’s worth of zinc, iron, B vitamins and more from one product ups your likelihood of getting a surplus. This is especially true if you take supplements or have more than one fortified food a day. If you want a boost, buy brands fortified with no more than 50 percent of the DV for any nutrient.

Consistently going far above the daily allowance can push you toward your tolerable upper intake level (UL), the point at which good nutrients can become dangerous. One European study suggested that people who ate large amounts of dairy could exceed the UL for calcium when adding things like calcium-fortified orange juice and oatmeal. Passing the daily 2,500-milligram limit regularly can cause constipation and kidney problems. Too much zinc may reduce immune function and HDL (good) cholesterol levels.

The best balance: Skip products that pack 100 percent of your DV for any one nutrient. Consume plenty of whole foods instead.

Once only health food staples, chips, spice concoctions and salad mixes made of sea plants like nori and kombu are now in the grocery. You can also find this power green—which has been linked to heart health—in sushi rolls and seaweed salads. The problem? Seaweed is often super rich in iodine. Too much can lead to thyroid problems, which can cause weight fluctuations. In one study, a 39-year-old woman was diagnosed with hyperthyroidism after downing tea that contained kelp for four weeks.

The best balance:I generally recommend that clients get their kelp fix safely by stopping at one fresh seaweed salad (in addition to sushi) once a week. Steer clear of the teas, unless prescribed by a doc, and keep seaweed snacks to one serving a day. If you notice fatigue or weight changes, though, cut them out completely.

Cynthia Sass, MPH, RD, is Health’s contributing nutrition editor, and privately counsels clients in New York, Los Angeles, and long distance. Cynthia is currently the sports nutrition consultant to the New York Rangers NHL team and the Tampa Bay Rays MLB team, and is board certified as a specialist in sports dietetics.

Coffee in your veins may actually be healthy

Published Monday in the medical journal Heart, the study involved more than 25,000 male and female workers, who previously showed no signs of heart disease, looking for calcium buildups indicating plaque growth that can cause heart attacks and strokes.

The results showed that those who drank the least amount of coffee, and the most, had a larger amount of calcium in their arteries than those who consumed a moderate amount.

Interestingly, researchers also discovered that the findings were consistent through different subsectors, such as smokers, drinkers and those with obesity issues.

“While this study does highlight a potential link between coffee consumption and lower risk of developing clogged arteries, more research is needed to confirm these findings and understand what the reason is for the association,” Victoria Taylor of the British Heart Foundation told the BBC.

Taylor also noted that the results should not be generalized because different cultures have distinct lifestyle and dietary customs that may also contribute to cardiovascular health.

Eating Peanuts May Be a Low-Cost Way to Improve Your Cardiovascular Health

But don’t go nuts

Eating peanuts could be associated with a longer, healthier lifespan and particularly a reduced risk of cardiovascular-related deaths such as heart attacks and strokes, a new study has found.

Researchers from Vanderbilt University and the Shanghai Cancer Institute examined nut intake for people from different ethnic groups and lower-income households.

As peanuts (which are actually legumes) are rich in nutrients and are inexpensive to buy, they could be a cost-effective way to improve cardiovascular health, reports Science Daily.

“In our study, we found that peanut consumption was associated with reduced total mortality and cardiovascular disease mortality in a predominantly low-income black and white population in the U.S., and among Chinese men and women living in Shanghai,” said author of the study, Xiao-Ou Shu.

Previous studies have linked eating nuts to a lower mortality but had generally focused on higher-income, white populations. Researchers claim the new study published in the journal JAMA Internal Medicine is the first to discover all races could potentially benefit from eating nuts.

They examined three large groups involving more than 70,000 black and white men and women living in the U.S. and more than 130,000 men and women living in Shanghai.

The results found that those who ate peanuts across all three groups had improved total mortality and less cardiovascular disease.

But scientists warn that the study was based on observational data collected from questionnaires, rather than clinical trials, so they cannot determine whether peanuts are specifically responsible for a lower risk of death.

“The findings from this new study, however, reinforce earlier research suggesting health benefits from eating nuts, and thus are quite encouraging,” said William Blot, co-author of the study.

While peanuts may be linked to better cardiovascular health, experts caution against eating too many, especially salted nuts, as they are high in calories.

Researchers say a small handful of nuts could be beneficial if eaten as part of a well-balanced diet.

The Best Workout for Weight Loss

Why intensity matters in exercise

Everyone knows that cardio exercise—by way of a bike ride or a sprint—is key to weight loss. But a high-intensity cardio workout may do a better job of decreasing blood sugar levels than lower intensity exercise, according to a new study in Annals of Internal Medicine.

The study assigned 300 obese people to a group: one that exercised with low intensity for long periods of time or another that engaged in high-intensity workouts for short durations. By the end of six months, people in both groups experienced similar levels of weight loss. But those who had exercised with higher intensities saw reduced two-hour glucose levels, a key measure for predicting conditions like heart disease and stroke. People in the high-intensity group saw a 9% improvement in glucose tolerance, compared to a negligible change in people who took part in low-intensity exercise.

Increasing the intensity of a workout isn’t beyond the reach of most exercisers, according to lead study author Robert Ross, a researcher at Queen’s University in Kingston, Ontario. “Higher intensity can be achieved simply by increasing the incline while walking on a treadmill or walking at a brisker pace,” Ross says.

Still, while high-intensity exercise may have some unique health benefits, the study showed that any exercise is better than none. People who exercised lost 5-6% of their body weight, a 4- to 5-centimeter reduction in waist size.

The study challenges the way public health officials tend to think about the health benefits of exercise. Health organizations often issue guidelines based on time spent exercising. Instead, the study suggests, health officials should consider intensity as well.

7 Signs Your Child’s School Has Unvaccinated Students

The resurgence of the measles has drawn scrutiny to California’s fairly lenient vaccine policy, which allows parents to choose a personal-belief exemption to avoid vaccinating their kids. And while parents can send their non-inoculated children to school, the state also publishes detailed information on the vaccination rates at every public and private school in the state.

By comparing this information with characteristics of each school, we were able to draw a detailed picture of what sort of schools are attended by children of vaccine-skeptic parents. Here’s a breakdown by a few different school characteristics.

Vaccination rates go down with the percentage of students receiving free or reduced lunch—which is the best school-by-school economic indicator available. In other words: The better off the parents are, the more statistically likely they are to apply for personal-belief exemptions against the otherwise mandatory vaccinations.

Though it’s less commonly discussed, the religious affiliation of a school is also a useful predictor of vaccination rates. (As with all statistical correlations, this does not mean it is the religion that is dictating the choice not to vaccinate.) Baptist and Calvary Chapel schools are particularly likely to have unvaccinated students, though overall, private religious schools have higher vaccination rates than non-religious private schools.

And though they account for only 661 students, Waldorf schools (as identified by the name of the school) have extremely high rates of personal-belief exemptions, to the tune of 38 percent. Mother Jonescaught up with a dean at one such Waldorf school who explained that, while there was no recommended policy on vaccines, she was accepting of whatever choice parents made.

The raw data for this story is available for download on TIME’s GitHub account. The vaccination data was matched to public and private school registries as well as data on free and reduced lunch programs by school. The correlation between the percentage of students receiving free or reduced lunch and the rate of personal belief exemptions is -0.29, and the correlation with the number of enrolled students is -0.18.

It’s Really Easy for Teens to Buy E-Cigs Online

Most popular e-cigarette sites fail to verify the age of their clients, finds a new study

Young people under age 18 can buy e-cigarettes online, even in states where it’s illegal, a new study shows.

North Carolina researchers asked 11 teens between ages 14 to 17 who didn’t smoke to try to buy e-cigarettes online from 98 of the most popular Internet vendors. The sale of e-cigarettes to minors in North Carolina is illegal—but of the 98 orders, only five were rejected based on a failed age verification. Eighteen orders failed for problems unrelated to age, like website issues. Overall, the minors made 75 successful orders.

The teens were also asked to answer the door when deliveries were made. None of the companies attempted to confirm age at delivery, and 95% of the time, the orders were just left at the teens’ doors.

The findings are concerning for any state trying to regulate youth access, the authors say. Currently, there’s no federal law forbidding the sale of e-cigarettes to minors, despite the fact that they contain nicotine, which is addictive. In 2014, the U.S. Food and Drug Administration (FDA) proposed that e-cigarettes fall under their regular tobacco regulation jurisdiction, but the proposal is still not a codified law. “It may be several years before federal regulations are implemented,” the study authors write.

Some states have stepped in and banned the sale to minors within their borders. So far 41 states and the U.S. Virgin Islands forbid such transactions, or have pending legislation to do so.

But as the new study suggests, young people can easily get e-cigarettes online if they want them. “Without strictly enforced federal regulations, online e-cigarette vendors have little motivation to decrease profits by spending the time and money it takes to properly verify customers’ age and reject underage buyers,” says study author Rebecca S. Williams, public health researcher at the University of North Carolina at Chapel Hill.

None of the vendors complied with North Carolina’s e-cigarette age-verification law. The majority of U.S. carriers, including USPS, UPS, FedEx, and DHL, ban the delivery of cigarettes, only allowing the delivery of tobacco products from a licensed dealer or distributor to another licensed dealer or distributor. If these rules were extended to e-cigarettes, the study authors argue it would essentially shut down a major loophole in access.

Getting proposed rules like the FDA’s passed takes time, but when it comes to the safety of children, the researchers argue there needs to be more urgency. Prior data has shown that from 2011 to 2013, the number of young Americans who used e-cigarettes but not conventional cigarettes more than tripled, from 79,000 to over 263,000. The study authors conclude that the ease with which teens can get e-cigarettes online—in a state that forbids the practice—stresses the need for more regulation, and fast.

The drugs can increase the risk of death for certain people with dementia

Antipsychotic drugs are being over-prescribed to men and women with dementia, according to a new report from the federal government.

The report published on Monday shows that around one third of older adults with dementia living in nursing homes had been prescribed an antipsychotic in 2012, as well as 14% of older adults with dementia who lived outside a nursing home. The U.S. Government Accountability Office (GAO) discovered the numbers when reviewing Medicare’s prescription drug program.

The high number of prescriptions is a concern since the U.S. Food and Drug Administration (FDA) has warned that antipsychotic drugs can increase the risk of death for certain people with dementia. The officials note that while the Department of Health and Human Services (HHS) has taken steps to address the use of antipsychotic drugs in nursing homes, it still has more outreach to do to educate people about the hazards of prescribing the drugs.

The report shows that patients with dementia are often given the drugs at a hospital, possibly to treat the irritation and mood swings caused by the disorder, and then the drugs continue to be used when the patients enter a nursing home. The drugs are most often prescribed when facilities have low staff numbers.

“Educational efforts similar to those provided for nursing homes should be extended to other settings,” the GAO study’s authors write. The agency recommends more education be provided for caregivers working with patients living at home or in assisted facilities.